1. The Field of the Invention
The present invention relates to single mode vertical cavity surface emitting lasers (VCSELs). More particularly, the present invention relates to systems and methods for VCSELs with varying reflectance and absorption across the VCSELs aperture.
2. Background and Relevant Art
Vertical cavity surface emitting lasers are continuing to evolve and are becoming increasingly useful in many applications. Because VCSELs emit from a direction perpendicular to the active region, they are well suited for low-cost wafer-scale fabrication. They are also suitable for array applications.
VCSELs typically have a short cavity length which implies that there is limitations on the relationship between the cavity resonance and the gain bandwidth. VCSELs may only have a single longitudinal mode. However, the cavity diameter of a VCSEL is relatively large and may permit more than one transverse spatial modes. In other words, VCSELs may be multi-mode devices. In a wide variety of applications, it is desirable to have a single mode output. The challenge faced today is the ability to reliably manufacture a VCSEL that is single mode.